The present invention relates to an integrated air compression, cooling and purification unit and air compression, cooling, and purification process. In particular, it relates to cryogenic air separation units and air separation processes using the air compression, cooling, and purification unit and process.
Certain markets, in particular for the conversion of natural gas, require large amounts of oxygen; therefore, increased sizes of air separation units. It is therefore necessary to increase the dimensions of the air compression systems for the air separation unit.
Generally, compressors with intercoolers are used to feed air separation units. For large plants, the cost of these compressors becomes prohibitive and their size makes them expensive to install.
To get around this problem, several compressors can be used in parallel but this is not very economical.
Usually these large compressors are powered by gas turbines or steam turbines, since the size of electric motors is limited. The steam turbines use the steam generated by the natural gas conversion processes. It is also known that gas turbines use axial compressors to treat air flows much larger than those used for air separation. However, these compressors are adiabatic and their energy consumption is disappointing, or even incompatible with air separation, since the heat of compression is not recycled.
It is known from U.S. Pat. No. 4,461,154 that air compressed in an adiabatic compressor may be used to preheat boiler feed water. U.S. Pat. No. 6,117,916 describes the use of heat from an adiabatic compressor to warm a working fluid before sending the air from the compressor. The air is then further cooled and sent to an air separation unit.